Field of the Invention
The subject invention is related to a process for the epoxidation of olefin with peroxide, particularly related to a process for epoxidation in a flow reactor which may increase the selectivity of epoxidation of olefin.
Description of the Related Art
There are many methods for the epoxidation of olefin, for example, Ullmann's Encyclopedia of Industrial Chemistry (Chapter: Epoxide, Wiley-VCH, 2000) discloses that epoxidation of olefin can be carried out with peroxy acid, hydrogen peroxide, halogenated alcohol or molecular oxygen. Dienes are commonly epoxidized with peroxy acid, such as peracetic acid. U.S. Pat. No. 2,716,123 A (1955, UCC) discloses a process in which diene was added dropwise with a 25.5% peracetic acid in acetone solution at a temperature of 20 to 40° C. over a period of 2 to 3 hours for a reaction over 11 to 16 hours, through which the cycloaliphatic esters of Formula 1, Formula 3, Formula 5, Formula 7 and Formula 9 can be epoxidized into the cycloaliphatic diepoxy compounds of Formula 2, Formula 4, Formula 6, Formula 8 and Formula 10 with yields of 85.5%, 84%, 85.4%, 95% and 79%, respectively.

GB 735974 A (1955, UCC) discloses epoxidizing Formula 11 into Formula 12 with peracetic acid obtained by oxidation of acetaldehyde. U.S. Pat. No. 3,275,661 A (1966, Ciba) discloses adding a 42% peracetic acid over 1 hour at a temperature of 30° C. into benzene solution containing the diene compound of Formula 13 and sodium acetate, and maintaining the reaction under 30° C. for 4 hours to produce the diepoxide of Formula 14. JP 2006-188476 A (2006, Daicel) discloses a process for producing high-purity cycloaliphatic diepoxide in which peracetic acid with a water content of 0.8 wt. % or less is added at 30° C. for a reaction for 3 hours, and which can epoxidize the cycloaliphatic diolefmic compound of Formula 15 to the cycloaliphatic diepoxide of Formula 16.

U.S. Pat. No. 8,697,895 B2 (2014, DOW) discloses epoxidation of propene, using a titanium silicalite-1 (TS-1) catalyst, methanol as solvent with a non-reactive co-solvent, wherein the co-solvent has a solubility dispersion force parameter δD of 0.4 to 1.0, a polar force parameter δp of 0.0 to 0.5, and a hydrogen bonding force parameter δH of 0.0 to 0.3. Use of co-solvent can reduce the amount of methanol solvent used, and further reduce alcoholysis. Furthermore, since the co-solvent can be separated from the aqueous layer by decanting and most of the by products are dissolved in the aqueous layer, the organic layer may be returned to reaction without byproduct accumulation, allowing a simplified recycling procedure. Another advantage is that the epoxidized product can enter the organic phase of the co-solvent and thus allows a reduced plugging of the catalyst pores to increase catalyst lifetime. EP 2462130 B1 (2013, DOW) also discloses epoxidation of propene with TS-1 catalyst, methanol solvent and non-reactive co-solvent(s) having solubility parameters similar to propylene oxide, which can reduce the amount of methanol solvent required, reduce alcoholysis by-products, increase selectivity of epoxidized products, increase catalyst lifetime and allow a simplified recycling procedure.
In a conventional batch reaction for epoxidation of olefin with peroxides, addition of peroxides should be controlled at a lower temperature and for a long time; in this case, a bigger reactor takes more time and the temperature is harder to control, which can raise safety concerns. PCT/EP2001/003875, JP 5163921 B2, JP 2009-256217 A, JP 2009-263240 A disclose processes for the epoxidation of olefins with a micro-reactor, which is safer and allows continuous production; among them, JP 2009-263240 A discloses oxidizing acetaldehyde with oxygen and cobalt catalyst in a micro-reactor, obtaining 40% peracetic acid through distillation, and then, in a stainless steel tube with 0.26 mm inner diameter, epoxidizing the aliphatic diolefinic compound of formula (1) into the aliphatic diepoxide of formula (2) with a yield of 79%.
For epoxidation of olefin with peroxides, in order to suppress side reactions of hydrolyzing the epoxides, the reaction should be carried out at a lower temperature and for a long time; however, this imposes a significant limitation on production capacity. By epoxidizing vegetable oil with peracetic acid, Campanella, A. and Baltanás, M. A. conducted further studies on hydrolysis (Chemical Engineering Journal 2006, 118, 141-152; Latin American Applied Research 2005, 35, 211-216 and 205-210), and found that peracetic acid, carboxylic acid, proton acid, water and hydrogen peroxide will cause hydrolyzation. Since most hydrolyzing reactions are related to proton acid, it is common to add a buffer agent such as acetate salts or phosphate salts to the reaction for controlling pH value, or use anhydrous peracetic acid obtained through acetaldehyde oxidation process to avoid hydrolyzation of epoxides caused by proton acid, water and hydrogen peroxide. However, it is still not possible to avoid hydrolyzation of epoxides caused by peracetic acid and carboxylic acid.
For epoxidation of olefin with peroxides, it is difficult to simultaneously improve both conversion rate and selectivity. Especially for epoxidation of diolefin, at a high conversion rate, though monoepoxide in the products is reduced, hydrolysate selectivity is higher; conversely, at low hydrolysate selectivity (e.g. at low temperature or low reactant concentration), higher monoepoxide selectivity is found.